Corrosion of metal in the presence of water is a challenging and common problem in a variety of industries. The corrosion can be generalized or localized. Corrosion can be a serious problem as it can cause deterioration of manufactured products by damaging their structure and ultimately even rendering some products useless. Allowing corrosion is not cost efficient and can inhibit productivity. Understanding and preventing corrosion has proven to be a difficult challenge for maintaining infrastructures, machinery, and products subject to corrosion.
For example, one area where corrosion can be an issue is in the fabrication of integrated circuits and other electronic devices. Typically, multiple layers of conducting, semiconducting, and dielectric materials are deposited onto or removed from a substrate surface. As layers of materials are sequentially deposited onto and removed from the substrate, the uppermost surface of the substrate may become non-planar and require planarization. Planarizing a surface, or “polishing” a surface, is a process whereby material is removed from the surface of the substrate to form a generally even, planar surface. Planarization is useful in removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials. Planarization is also useful in forming features on a substrate by removing excess deposited material used to fill the features and to provide an even surface for subsequent levels of metallization and processing.
Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Chemical-mechanical planarization, or chemical-mechanical polishing (CMP), is a common technique used to planarize substrates. CMP utilizes a chemical composition, known as a CMP composition or more simply as a polishing composition (also referred to as a polishing slurry), for selective removal of material from the substrate. Polishing compositions typically are applied to a substrate by contacting the surface of the substrate with a polishing pad (e.g., polishing cloth or polishing disk) saturated with the polishing composition. The polishing of the substrate typically is further aided by the chemical activity of the polishing composition and/or the mechanical activity of an abrasive suspended in the polishing composition or incorporated into the polishing pad (e.g., fixed abrasive polishing pad).
The chemical-mechanical polishing of cobalt (Co) is becoming increasingly important in advanced circuit integration techniques. Although compositions designed for polishing copper (Cu) are known in the art, these polishing compositions do not always provide a combination of satisfactory polishing performance for cobalt while managing corrosion to desired levels. Copper corrosion inhibitors may not adequately protect the cobalt surface from undesirable chemical attack and etching.
A need remains for methods of inhibiting corrosion of a substrate, including, for example, a substrate that contains cobalt. There is also a need for polishing compositions and methods that provide effective cobalt removal rates, while suppressing the corrosion of cobalt. The invention provides such polishing compositions and methods. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.